Renal protection effect of gastric bypass and its mechanism in type 2 diabetes mellitus rats

Objective　To observe the renal protection effect of gastric bypass, and explore its possible mechanism in type 2 diabetes mellitus (T2DM) rats. Methods　Forty SD rats were randomly divided into normal control group (n=8) and diabetes model group (n=32). Rats in diabetes model group were injected STZ (35 mg/kg). After the diabetes model was reproduced successfully, they were randomly divided into diabetes control group (n=8), diabetes sham-operation group (n=8) and diabetes operation group (n=14). Roux-en-Y gastric bypass was performed in rats of diabetes operation group. The fasting blood glucose (FBG), renal hypertrophy index (kidney weight/body weight), blood urea nitrogen (BUN), serum creatinine (Cr), activity of total superoxide dismutase (TSOD) and glutathione peroxidase (GSH-PX), content of malondialdehyde (MDA), activity of aldose reductase (AR) and AR mRNA expression in the kidney were determined 8 weeks after operation. The renal tissue was examined with light microscopy. Results　Compared with normal control group, the renal hypertrophy index, FBG, BUN, Cr, content of MDA, activity of AR and AR mRNA expression in the kidney significantly increased in diabetes control group and diabetes sham-operation group, while the activity of TSOD and GSH-PX decreased (P<0.05). Compared with diabetes control group and diabetes sham operation group, the kidney hypertrophy index, FBG, BUN, Cr, content of MDA, activity of AR and AR mRNA expression in diabetes operation group markedly decreased (P<0.05), while the activity of TSOD and GSH-PX increased (P<0.05). HE staining showed that the renal structure was normal in normal control group. The glomeruli became obviously enlarged, mesangial proliferation was marked, and the mesangial zone expanded in diabetes control group and diabetes sham-operation group. Such renal changes appeared milder in diabetes operation group. Conclusion　The gastric bypass could protect the kidney of T2DM rats, which may be ascribed to reduction of oxidative stress and inhibition of AR mRNA expression and polyol pathway in renal tissue. DOI: 10.11855/j.issn.0577-7402.2014.06.06